Self-agglomerated collagen patterns govern cell behaviour

Abstract

Reciprocity between cells and their surrounding extracellular matrix is one of the main drivers for cellular function and, in turn, matrix maintenance and remodelling. Unravelling how cells respond to their environment is key in understanding mechanisms of health and disease. In all these examples, matrix anisotropy is an important element, since it can alter the cell shape and fate. In this work, the objective is to develop and exploit easy-to-produce platforms that can be used to study the cellular response to natural proteins assembled into diverse topographical cues. We demonstrate a robust and simple approach to form collagen substrates with different topographies by evaporating droplets of a collagen solution. Upon evaporation of the collagen solution, a stain of collagen is left behind, composed of three regions with a distinct pattern: an isotropic region, a concentric ring pattern, and a radially oriented region. The formation and size of these regions can be controlled by the evaporation rate of the droplet and initial collagen concentration. The patterns form topographical cues inducing a pattern-specific cell (tenocyte) morphology, density, and proliferation. Rapid and cost-effective production of different self-agglomerated collagen topographies and their interfaces enables further study of the cell shape-phenotype relationship in vitro. Substrate topography and in analogy tissue architecture remains a cue that can and will be used to steer and understand cell function in vitro, which in turn can be applied in vivo, e.g. in optimizing tissue engineering applications.

Evaporation-driven liquid flow in sessile droplets

“…at the contact line, where the evaporation is strongest and the particle transport largest. 129 The altered rheology can affect both the internal flow and the motion of the contact line and thereby give rise to peculiar deposition patterns, 137 such as regularly spaced concentric rings, 131,138 striped, fingered or branched structures. 139,140…”

Multiscale characterization of pathological bone tissue

“…It is important to note that, when analyzing bone samples by using polarized light microscopy, birefringence is thought to be an indication regarding the orientation of collagen fibers as collagen is an anisotropic material. When the collagen fibers are parallel to the light source, they appear darker and when the collagen fibers are perpendicular to the light source, they appear brighter (Bromage et al, 2003 ; Dede Eren et al, 2021 ) which helps identify the orientation of collagen fibers. However, one should be careful while relying on only polarized light microscope when determining the orientation of collagen fibers due to an effect called differential birefringence which is based on the thickness of the section (Bromage et al, 2003 ) taken from bone samples and it is crucial to be consistent in terms of the thickness of the sample during sample preparation.…”

Microfluidically Aligned Collagen to Maintain the Phenotype of Tenocytes In Vitro

“…It is important to mention that in our study we used cells from an already comparatively high and therefore more demanding passage number 5, while studies typically use lower and “easier” passage numbers 3 or 4. [ 9,13,26 ] On day 1, we observed that tenocytes cultured on collagen fibers obtained with Rhombus 50 and Line devices displayed a significantly smaller cell area when compared with TCP controls (Figure S5A,C, Supporting Information). In addition, the eccentricity (i.e., the ratio of the distance between the foci of an ellipse and its major axis length, which can take values between 0, for a circle, and 1) of cells cultured on collagen micropatterns from Circle 50 and Square 50 devices was significantly higher than that of cells cultured on collagen from Blank devices (Figure S5A,C, Supporting Information).…”